1. Field of the Invention
The present invention relates generally to platforms or support structures and, more specifically, to a platform including a self-locking mechanism.
2. State of the Art
In many circumstances, it becomes desirable to provide a temporary elevated working surface for the support of one or more individuals. For example, in the construction industry, it is often necessary to perform work on a ceiling, the upper section of a wall, or some other elevated structure. Such an activity might include, for example, hanging drywall, painting, applying stucco, laying brick or performing remedial work on a given structure.
Various structures are used to provide such an elevated working surface. For example, various types of ladders are often used to provide access to an elevated location. However, ladders only provide an elevated working surface for a limited lateral work area. Thus, if one's work or activity requires access to an area spread over a relatively large lateral distance, use of a ladder requires repeated ascent, descent and moving of the ladder to perform the activity. Additionally, a ladder conventionally only provides an elevated working surface for one individual at a time.
Another structure which provides an elevated working surface is a scaffold. A scaffold includes a framework which supports one or more elevated planks or platforms. The platforms generally provide a horizontally or laterally extending surface on which one or more individuals may access a relatively large area at a desired vertical elevation. The planks or platforms are conventionally movable and may be repositioned vertically and/or horizontally thereby providing considerable flexibility with regard to the elevated areas a user may access thereby.
Scaffolding, while providing relatively good access to elevated areas for one or more individuals, often requires time consuming assembly and disassembly of the scaffold framework when it is desired to laterally move the scaffolding any significant distance. Thus, in instances where the work to be performed by an individual requires substantial continual lateral movement over a relatively short period of time, scaffolding becomes a cumbersome and inefficient solution.
Another solution which has been employed is the use of a plank or platform placed on a pair of elevated supports. For example, a wooden plank may be placed on a pair of supports, often referred to as ladder jacks, with the supports each being structurally coupled to one of a pair of spaced apart ladders. In a more simple arrangement, the plank may be placed directly on a rung of one of a pair of spaced apart step ladders. Other platforms, including longitudinally extensible platforms such as are shown in U.S. Pat. Nos. 3,703,220 issued Nov. 21, 1972, and U.S. Pat. No. 5,067,589 issued Nov. 26, 1991, maybe used in a similar manner with a pair of laterally spaced supports.
The use of a plank or platform with a pair of readily movable, laterally spaced supports provides an elevated working surface for one or more individuals and for a relatively large working area. Furthermore, such an arrangement allows for simple relocation of the elevated working surface and transportation thereof from one location to another. Additionally, the use of extensible planks, such as disclosed in the above-referenced U.S. Patents, in conjunction with a pair of laterally spaced supports offers additional flexibility by providing an elevated working surface for a variety of circumstances, locations and configurations. For example, an extensible platform may be longitudinally extended to provide an elevated working surface over a relatively wide horizontal distance and may be subsequently contracted for use in a relatively tight space. Additionally, such a platform may be contracted for storage and transportation thereof.
While, the arrangement of a plank or platform supported by a pair of laterally spaced supports provides a convenient and flexible solution in many circumstances, various functional and safety issues may arise in utilizing such an arrangement. For example, the simple placement of a plank or platform on top of a pair of supports gives rise to a situation where the end of the plank or platform may slip off one of the supports and cause the plank or platform, and anyone (or anything) supported thereby, to fall. Such slippage between the plank or platform and its supports may be due to, for example, continued lateral movement of an individual on the platform resulting in a series of small displacements of the platform relative to the supports. Also, slippage may occur between a platform and its supports when a user supported thereby applies a lateral force to a portion of an elevated structure thereby inducing a reactionary force within the platform and displacing the platform relative to its supports.
Some types of planks or platforms include one or more fixed hooks or similar structural members at each longitudinal end thereof configured to engage a cross-member of the laterally spaced supports and prevent relative lateral displacement therebetween. However, the use of fixed hooks to engage a support limits the flexibility of such an arrangement with respect to the relative placement of the plank or platform and the laterally spaced supports. Additionally, the use of fixed hooks assumes that the supports have an appropriately sized and configured cross-member for cooperative engagement therewith. In other words, the use of hooks to prevent lateral displacement of the plank or platform relative to its supports can be limiting with regard to which structures may be used as supports.
In view of the shortcomings in the art, it would be advantageous to provide a platform, including a longitudinally extensible platform, which provides an automatic lock or catch mechanism for preventing relative lateral displacement with a support member. It would also be advantageous to provide such a platform which is able to engage with a variety of support members to provide additional flexibility in its use as an elevated working surface.